San Diego

©  2009  Rose George

In far too many wastewater treatment plants, the methane that is created by digesting sewage sludge is simply burned off in flares, because plants don’t know what else to do with it. It’s an environmentally unfriendly practice, methane being a greenhouse gas, but it’s also a waste of a perfectly good energy source. Only a third of UK wastewater treatment plants use the methane, usually by generating electricity. Point Loma treatment plant in San Diego uses two-thirds of its methane to power the plant, but has to burn off a third because there’s simply too much sewage and methane for the plant’s power needs. A new scheme will see the extra third trucked miles away to “several locations around the region.” Power plants using fuel cells will turn the gas into enough electricity to power 2700 homes. The state will also buy some of the electricity to run another sewage plant, saving $78,000 in fuel costs a year. I’ve written about fuel cells before. They work well, but they’re expensive. The Point Lomo project is possible only because of big grants and subsidies. It all sounds very sensible, except for the trucking part. Here is a clear and helpful guide to how it will work.